n the late summer of 1965 a disorganized storm system formed
over the warm, tropical waters of the mid Atlantic. Soon the storm grew into a
high-powered cyclone—a twisting mass of wind and water that would torment the
Gulf Coast in the coming days. The National Hurricane Center gave it a
hauntingly innocuous name: Hurricane Betsy.

J.J. Westerink and R.A. Luettich,
all

Storm prediction was still in its infancy then and researchers could not get
a read on Betsy’s erratic path. She zigzagged north from Puerto Rico and first
seemed to be heading straight toward the Carolinas. At the last moment, however,
Betsy swerved toward the Bahamas, then again toward Florida, finally veering
west of the peninsula and straight toward Louisiana.

On September 9 Betsy hit the southern tip of the state. Almost every building
in the small coastal town of Grand Isle was quickly destroyed. With 150 mph (240
km/h) winds, Betsy barreled up the Barataria Basin toward New Orleans. Lake
Pontchartrain—which is just north of the city and is connected to the Gulf of
Mexico—swelled with raging waters. Easterly winds pounded the high waters, in
some areas easily topping the levees meant to protect the city. In streets in
the eastern part of town water reached the eaves of houses.

Betsy finally calmed near Little Rock, Arkansas. She had dropped only 4 in.
(100 mm) of rain on New Orleans and had claimed 81 lives and caused more than $1
billion in damage. Unlike any storm before it, Betsy made clear that the city
was all too vulnerable to hurricanes. Cradled in a wide southern meander of the
Mississippi River just north of the Gulf of Mexico, New Orleans is surrounded by
Lake Pontchartrain to the north, Lake Borgne to the east, and lakes Cataouatche
and Salvador to the south. This ring of freshwater is also surrounded by
hundreds of square miles of wetlands and the Gulf of Mexico. To make matters
worse, most of the city is below sea level.

Soon after the damage from Betsy was assessed, Congress made a historic
decision to appropriate federal funds to build a system of levees to protect the
city from a similar storm in the future. Its cultural significance aside, New
Orleans was fast becoming the most important port in the nation—feeding
commodities up the Mississippi to all of the Midwest and serving as an important
base for the burgeoning oil and gas industry. Congress was not about to let it
wash away.

Today New Orleans rests within a bowl formed by 16 ft (4.9 m) tall levees,
locks, floodgates, and seawalls, the edge of the bowl extending for hundreds of
miles. It is bisected from west to east by the Mississippi River, which is also
contained within massive engineered embankments. Water flows through and all
around the city while its residents go about their daily routines. A system of
levees forming a ring around the northern half of the city to protect it from
surging waters in Lake Pontchartrain is set to be completed within the next
decade. Construction of a similar system around the southern half of the city
will probably take several years longer than that.

But almost 40 years after beginning these projects, the U.S. Army Corps of
Engineers is in the midst of reassessing them on the basis of an ominous
question: Are the protective barriers high enough?

The design of the original levees, which dates to the 1960s, was based on
rudimentary storm modeling that, it is now realized, might underestimate the
threat of a potential hurricane. Even if the modeling was adequate, however, the
levees were designed to withstand only forces associated with a fast-moving
hurricane that, according to the National Weather Service’s Saffir-Simpson
scale, would be placed in category 3. If a lingering category 3 storm—or a
stronger storm, say, category 4 or 5—were to hit the city, much of New Orleans
could find itself under more than 20 ft (6 m) of water.

Some experts worry that even a less severe storm could flood the city. In the
40 years since the design criteria were established for New Orleans’s hurricane
protection levees, southeastern Louisiana’s coastline has been
subsiding—settling in on top of itself—even as the natural height of the sea
rises. A century ago any hurricane heading toward New Orleans would have had to
traverse a 50 mi (80 km) buffer of marshland. Today that marsh area is only half
as broad and the hurricane would be striking a city that itself sinks lower
every day.

or at least 7,000 years the incredible charge of the
Mississippi River has made and destroyed dozens of courses throughout southern
Louisiana. As water from an area that now extends over 31 states—from as far
west as Montana and as far east as New York—washed through the delta, sediment
flooded over the river’s edge, building bayous and uplands that eventually
became thick enough to send the river in a new direction. After 1718, when a
Frenchman named Jean-Baptiste Le Moyne de Bienville founded New Orleans on one
of those precarious ridges, the river would change course no more.

The location of New Orleans was ideal for portage because traders could
access the Mississippi from the gulf via Lake Pontchartrain, avoiding the
treacherous lower 100 mi (160 km) of the river. In the late 1800s Corps
engineers began constructing levees of a more permanent type along the river’s
channel and cleared sunken ships, dead trees, and other detritus from its outlet
to the gulf. With the levees in place, the lowlands beyond the river did not
flood as often, and people began building homes in areas once reserved for
alligators, mosquitoes, and yellow fever.

In the spring of 1927, the Mississippi River flooded in a way that had never
been recorded before. Raging waters tore through levees in Arkansas,
Mississippi, and Louisiana, killing at least 1,000 people and inundating 1
million homes. It was the mighty river’s last hurrah. Soon thereafter, Congress
directed Corps engineers to straighten the river in places, add floodgates in
others, and increase the height of its levees all the way from Vicksburg,
Mississippi, to the gulf. At the same time, New Orleans began developing what
has become the most sophisticated drainage network in the United States. Today
almost 200 mi (320 km) of canals lead to 22 pumping stations located in the low
points of the city. The stations are able to pump 35 billion gal (132.5 million
m3) of water per day from the city into the surrounding lakes. They
could fill the Superdome stadium, the home of the New Orleans Saints football
team, to capacity in 35 minutes.

The city is now well protected from floodwaters from the Mississippi. Storm
surge from hurricanes, however, is another matter.

Since variations in the storm’s profile occur more
rapidly on land, the AdCirc nodes there become more refined. In the open
ocean the nodes are spaced every 15.5 mi (25 km), but in New Orleans they
are as close as 330 ft (100 m). A snaking line of highly refined nodes
represents the Mississippi River, above. In a bathymetric representation
of the same area, top, New Orleans surrounds the 109th flood
gauge.

In the Flood Control Act of 1965, passed shortly after Hurricane Betsy
pummeled New Orleans, Congress appropriated funds to increase the height of the
levees around the northern side of the city, where Lake Pontchartrain ominously
abuts what used to be swampland but today is suburbia. With help from a
meteorologist from the National Weather Service, Corps engineers determined a
wind speed and pressure that they felt closely characterized Hurricane Betsy.
The work was done before the development of the Saffir-Simpson scale, which
today is used to categorize hurricanes. At the time Corps engineers called their
approximation a standard project hurricane (SPH), equivalent
to what today would be called a fast-moving category 3 storm.

Engineers determined that the levees bordering the Mississippi River as it
passes through the city were sufficient to withstand any surge produced by an
SPH. So the idea was to create a rough semicircle of
hurricane levees along the boundary of the lake that would start at the
Mississippi River levee west of New Orleans and end at a point to the east of
the city. Additionally, levees, floodwalls, or both would have to be constructed
around each of the area’s drainage canals, as well as around bridges crossing
those canals and around the pump stations emptying into the lake.

As the program continued, one project spiraled into another. In 1986 Congress
authorized the Corps to build a system of levees around the southern half of the
city, also forming a rough semicircle extending to and from the Mississippi
River levees. In the mid-1990s Congress continued to expand the southern
protection zone, requiring a total of about 65 mi (105 km) of levees and thereby
protecting tens of thousands of homes.

“People live their entire lives in an area that is below sea level and it
just becomes a fact of life,” says Al Naomi, the project manager for all of the
Corps’s hurricane protection levees in southeastern Louisiana. “They just keep
taxing themselves for drainage and levee improvements to make sure they can stay
here. Staying dry is very important in this city. People will vote for improving
drainage before they’ll vote for improving schools.”

Naomi was in high school when the Corps began constructing the levees
bordering Lake Pontchartrain. And he will probably retire long before the
barriers around the southern part of the city are completed—in 2018 if all goes
as expected. In the next few years he will also oversee the beginnings of three
Corps levees that are now being constructed around less populated areas outside
of New Orleans: Venice, Grand Isle, and Larose. About $900 million has already
been spent on Louisiana’s hurricane protection program, and before the current
projects are complete more than $1.4 billion will be required.

The basic framing system consists of continuous girder trusses
spanning the 90 ft (27 m) distances between columns. These large spans and
floor-to-floor heights ruled out the use of conventional steel building
framing. The building’s gravity-load-carrying system contains more than
40,000 tons (36,000 Mg) of high-strength steel.

Congress is also currently spending millions of dollars on several Corps
studies to assess the feasibility of creating hundreds of miles of levees
throughout the marshland of southern Louisiana. Those projects—which would be
particularly difficult to construct owing to the scarcity of levee borrow
material in wetlands—would cost an additional $1 billion.

ven as the Corps approaches the long-awaited conclusion of
some of its first levee projects—with many more on deck—it finds itself in the
midst of a major reassessment to determine if any of the levees surrounding the
city will actually provide the level of protection for which they were designed.

In the mid-1960s, Corps engineers who were asked to model the storm surge
associated with an SPH did not have many tools at their
disposal, at least not by today’s standards. With wind speeds developed by the
U.S. Weather Bureau, they used variations of Newton’s second law to predict a
storm’s conservation of mass and momentum. The engineers created a hypothetical
storm in one-dimensional slices, eliminating the geometrical complexity of the
real world, then drove it on a straight line from the Atlantic perpendicular to
selected locations near the shore of the gulf.

Assuming a constant wind velocity over Lake Pontchartrain, the engineers
computed the buildup of water at the levees along the lake’s south shore on an
hourly basis. They ran simulations mimicking the characteristics of hurricanes
that hit New Orleans in 1915 and 1947 and then used the ratio between the actual
storm surge recorded during those hurricanes and their computed value to create
a factor of safety for the new levees.

“It was a very coarse approximation,” says Joannes Westerink, a professor of
civil engineering at the University of Notre Dame who specializes in
computational fluid dynamics. “But it’s what they could do at the time.”

Westerink and a colleague—Rick Luettich, a professor at the University of
North Carolina’s Institute of Marine Sciences—have developed a modern
hydrodynamic circulation model that seems magical by comparison. Their Advanced
Circulation Model for Coastal Ocean Hydrodynamics, or AdCirc, is a
two-dimensional numerical model that predicts long-term periods of circulation
along coastal shelves, coasts, and estuaries. It is used to predict a wide
variety of flows, but during the past decade the Corps has devoted millions of
dollars to improve its ability to model hurricanes. For the past four years
Corps engineers have been calibrating a model expressly designed to represent
the New Orleans area.

Red lines in the AdCirc grid, below, represent levees and other
structures that might slow or stop hurricane surge. Researchers are most
worried about surge buildup in Lake Pontchartrain, which surrounds the
164th flood gauge north of the city, opposite. Some models indicate that
surge in the lake from a strong storm could flood the city to a depth of
25 ft (7.6 m).

The numerical equations that underlie AdCirc are similar to the ones used by
Corps engineers back in the 1960s—each a variation on Newton’s second law. But
the solutions produced by AdCirc are sufficiently complex to create a
two-dimensional storm that actually moves within a defined geographic boundary.
The boundary—which includes the Atlantic coast all the way from Nova Scotia to
Argentina—is divided into a grid of nodes containing depth of water, land
structures, and any other real-world characteristics that would affect the
storm’s profile.

As recently as the 1980s, hurricane models were run on single processors,
vastly limiting the number of nodes that could be solved efficiently. Today,
AdCirc is run on parallel processors—as many as 256—and is capable of
continuously solving as many as 1 million geographic nodes. This processing
power is what enables AdCirc to solve such a large set of equations. In turn,
AdCirc enables modelers to initiate a hurricane simulation on the open sea,
where a storm’s path is more predictable and its characteristics can be closely
defined.

Because less information is required to accurately simulate a hurricane on
the open sea, the nodes in that area are not as rigorously defined as those near
the coastal shelf. In the areas of a boundary where more variation of depth
exists—on the coastal shelf and on land—the nodes contain highly refined
information so that they more effectively define variations in the storm. In a
visual representation, this boundary takes the shape of a finite-element grid.

The nodes in the middle of the ocean contain information based on a 15.5 mi
(25 km) grid, but they become increasingly refined as they approach the
shoreline. In the case of a boundary surrounding New Orleans, where the grid
extends inland all the way to Baton Rouge, the nodes over land are spaced every
330 ft (100 m) and include information about topography, canals, levees, and any
other land masses that might affect storm surge.

On a supercomputer at the Corps’s Waterways Experiment Station, in Vicksburg,
Mississippi, engineers run AdCirc simulations of Hurricane Betsy and of
Hurricane Andrew, a category 3 storm when it hit Louisiana in 1992. It takes
roughly an hour to run the calculations representing 24 hours in the life of the
storm. Eventually a trace of storm surge levels is produced at about 200
locations around New Orleans; Corps engineers then compare those results with
the actual surge levels recorded in those areas.

Jay Combe, a Corps engineer in charge of the modeling effort, meets every six
months with an advisory panel composed of several of the world’s premier
modeling experts to review the results. Once AdCirc has been refined to the
point where it satisfies Combe and the review committee, it will be used to
conduct a comprehensive reassessment of New Orleans’s existing and planned
hurricane levees.

Combe says that point should be reached this summer. “I think we’re getting
close to the right answer,” he says. “But I want to feel totally confident. And
I want our outside review team to feel that this is the best we can do with the
state of the art right now.”

Combe is cautious with his work because he knows how much is riding on it. In
the coming months Corps engineers will use AdCirc to determine if the levees
that have been going up around New Orleans for the past 40 years are tall enough
to resist storm surge from an SPH. Perhaps even more
important, when the model is ready Naomi will use it to determine what it would
take to protect New Orleans from a category 4 or 5 hurricane.

In 1999 the Corps was authorized by Congress to study the feasibility of
various proposals for protecting the city against such devastating storms. An
obvious possibility would be to raise the current levees to a height deemed
acceptable by an AdCirc analysis. That, however, would also require widening the
levees, which may not be possible in many areas because of the proximity of
homes. Among other alternatives, Naomi will investigate the possibility of
creating an immense wall between Lake Pontchartrain and the gulf to keep water
out of the lake during a severe storm. Such a project would involve constructing
massive floodgates at the Rigolets and Chef Menteur passes, where storm surge
would enter the lake.

According to Naomi, any concerted effort to protect the city from a storm of
category 4 or 5 will probably take 30 years to complete. And the feasibility
study alone for such an effort will cost as much as $8 million. Even though
Congress has authorized the feasibility study, funding has not yet been
appropriated. When funds are made available, the study will take about six years
to complete. “That’s a lot of time to get the study before Congress,” Naomi
admits. “Hopefully we won’t have a major storm before then.”

A
time-lapse simulation of Hurricane Betsy—with integrated wind speed and
direction—replicates the storm’s movement through Louisiana in 1965.
Several hurricane models are calibrated by the surge associated with
Betsy, which did not hit New Orleans directly but flooded much of the
city.

f a storm of category 4 or 5 were to hit New Orleans
before the city was adequately prepared, what toll would it exact?

In the 1980s Joseph Suhayda, then a coastal oceanographer in the civil
engineering department at Louisiana State University (LSU),
began to seek an answer to this question by simulating storms with a modified
version of a hurricane model used by the Federal Emergency Management Agency
(FEMA). Suhayda first began modeling the storms to help
parishes in southeastern Louisiana determine appropriate flood elevations for
FEMA’s National Flood Insurance Program. As his modeling
capabilities improved, he began to more closely investigate the level of
protection provided by the levees encircling New Orleans.

Suhayda’s model contains a geographic information system overlay that divides
a fairly large boundary, from Alabama to Texas, into 0.6 mi (1 km) grids
containing information about ground elevations, land masses, and waterways. The
FEMA hurricane model does not draw on the same processing
power as AdCirc and in general produces more liberal projections of flooding
from storm surges. But by solving numerical equations representing a storm’s
pressure, wind forces, and forward velocity, Suhayda was able to use the model
to predict the storm surge associated with an actual hurricane dozens of hours
before it hit land. By subtracting the elevations on a topographical map of
coastal Louisiana from those surge values, he was able to approximate the flood
risk of a given storm.

In the 1990s, Suhayda began modeling category 4 and 5 storms hitting New
Orleans from a variety of directions. His results were frightening enough that
he shared them with emergency preparedness officials throughout Louisiana. If
such a severe storm were to hit the city from the southwest, for instance,
Suhayda’s data indicate that the water level of Lake Pontchartrain would rise by
as much as 12 ft (3.7 m). As the storm’s counterclockwise winds battered the
levees on the northern shore of the city, the water would easily top the
embankments and fill the streets to a depth of 25 ft (7.6 m) or more.

Suhayda’s model is not the only one that describes such a catastrophe. A
model called SLOSH (Sea, Lake, and Overland Surges from
Hurricanes), which is used by the National Weather Service and local agencies
concerned with emergency preparedness, portrays an equally grim outcome should a
storm of category 5 hit New Orleans. The SLOSH model does
not contain nearly as many computational nodes as does AdCirc, it does not use a
finite-element grid to increase the resolution of the nodes on shore, and its
boundary is much smaller. Even so, its results are disheartening.

“Suppose it’s wrong,” says Combe, the Corps modeler. “Suppose twenty-five
feet is only fifteen feet. Fifteen feet still floods the whole city up to the
height of the levees.”

Experts say a flood of this magnitude would probably shut down the city’s
power plants and water and sewage treatment plants and might even take out its
drainage system. The workhorse pumps would be clogged with debris, and the
levees would suddenly be working to keep water in the city. Survivors of the
storm—humans and animals alike—would be sharing space on the crests of levees
until the Corps could dynamite holes in the structures to drain the area. In
such a scenario, the American Red Cross estimates that between 25,000 and
100,000 people would die.

That prospect—and the amount of time it would take the Corps to construct
adequate levee protection against a storm of category 4—have inspired Suhayda to
push for what he calls a community haven project. His idea is for the city to
construct a 30 ft (9 m) tall wall equipped with floodgates through the center of
town to protect the heart of New Orleans and such culturally important areas as
the French Quarter. That portion of the city lies between two bends in the
Mississippi River and is therefore already protected by adequate levees on three
sides. With its gates closed, the wall would complete a waterproof ring around
the area.

Suhayda says the wall would be cheaper and faster to build than the larger
projects under consideration by the Corps. It could be constructed along an
existing right-of-way and act as a sound wall most of time. “We’re going to
build sound barriers along most of these roads anyway,” Suhayda says. “So for a
small added cost, go ahead and make them capable of withstanding wind loads and
hydrostatic heads.”

The Corps would not necessarily be involved in the construction of such a
wall because the latter would be land based. Even so, Naomi is adamantly opposed
to the idea. “How do you protect people from two-hundred-mile-per-hour winds?”
he asks. “Where do they go? What buildings are designed to withstand that? Where
do they get their power and their food, and where do they rest their heads at
night? Just keeping the water out isn’t enough. You don’t want to give people a
false sense of security by saying that this is a refuge unless you have a place
for them to go.”

For the most part, New Orleans does not have places for people to go. The
American Red Cross no longer provides emergency shelters in the city because its
officials cannot guarantee the structural integrity of the locations. There
simply are not enough buildings in the area that could withstand the forces of a
category 4 or 5 storm.

During the past 10 years Marc Levitan, a wind and structural engineer and the
director of LSU’s Hurricane Center, has been involved in
hundreds of building investigations throughout New Orleans to determine if
certain structures could be used as so-called refuges of last resort. “With the
vast majority of them, if you really do an analysis, you really wouldn’t want to
use them,” he says. “They all have some sort of deficiency.”

Most people would not wish to remain in the city if a category 4 or 5 storm
were in prospect, but evacuating could be difficult. Experts say close to
400,000 people could be stranded in the city. There are an estimated 100,000
people without easy access to automobiles, and those who can drive may not be
able to do so. During Hurricane Andrew, interstates throughout the South were
brought to a standstill because simultaneous evacuations were taking place in
several states. The only major planning improvement since then has been the
decision to keep traffic away from the coast on both sides of evacuation
routes.

Complicating the difficulty in New Orleans is the fact that each of the
city’s three major evacuation routes is over or near water. Suhayda’s model
indicates that during a storm of category 5 Interstate 10, which is constructed
on piers for a distance of almost 20 mi (32 km) west of the city, could be
covered by more than 5 ft (1.5 m) of water.

ater has literally made New Orleans what it is today. Some locals
call southern Louisiana the re–United States because in essence the ground is
made up of sediment from throughout North America that has made its way down the
basin of the Mississippi. The decision to live in this place, however, has also
made water the enemy.

“We’re trying to enforce human decisions on a natural process,” says Naomi.
“What we’re trying to do is take a snapshot of geologic time and say, ‘This is
what we want; this is where we want to live.’ The question is, Is it going to be
feasible in the long term?”

Naomi says this question will not be answered with levee feasibility studies
alone. It will also require a more complete understanding of the natural
processes at work in and around New Orleans. For example, the wetlands of
coastal Louisiana, which would act as a buffer and slow any storm during its
approach to the city, are dying because the freshwater and nutrients that
historically flooded into them from the Mississippi can no longer escape the
river. At the same time, the sediment deposited here by the river long ago is
subsiding, and no new sediment is overflowing to replenish it.

The Corps estimates that in southeastern Louisiana a football field worth of
wetlands sinks into the sea every 30 minutes, leaving the residents of the area
more vulnerable to hurricanes every inch of the way.

In an attempt to curb this growing threat, or, as some refer to it, creeping
catastrophe, the Corps is developing a plan—in collaboration with the U.S.
Environmental Protection Agency, the Louisiana Department of Natural Resources,
and other state and federal agencies—to rehabilitate coastal wetlands throughout
Louisiana. Known as the Coast 2050 Plan, it would require $14 billion over the
next 30 years to restore natural drainage along the coast and direct the
movement of sediment from the Mississippi to rebuild marshes. It also calls for
the installation of sediment traps at key locations in the river, from which the
material would be pumped through 100 mi (160 km) long slurry pipelines to
rebuild wetlands and barrier islands.

Research conducted in the 1970s indicates that Louisiana’s coast has seen no
physical growth since the 1880s. By 1913 it was subsiding at a rate of about 7
sq mi (18 km2) per year. Since 1990 various groups have attempted to
stave off the effects of coastal erosion under the auspices of the Coastal
Wetlands Planning, Protection, and Restoration Act, but until now there has been
no large-scale collaboration.

Naomi says he will be keeping a close eye on the Coast 2050 Plan in the
future because he is certain it will affect his assessment of New Orleans’s
hurricane protection program. But does the question of subsidence raise a more
troubling issue?

“Everyone here sees different symptoms,” says Roy Dokka, a geology professor
at LSU and the head of the Louisiana Spatial Reference
Center. “If you’re a biologist you see the forest dying. If you’re running an
oil field down on the coast you see that the roads you used to drive down are
now under water during certain periods of time. If you’re an emergency
preparedness person you notice that the evacuation roads tend to flood earlier
than they did ten years ago.”

The true situation, however, is almost too grave to consider. “Coastal
Louisiana is sinking under its own weight,” Dokka says. “The ground in Louisiana
is ultimately going to go under.”

Indeed, the state is subsiding so quickly that the National Oceanic and
Atmospheric Administration’s National Geodetic Survey (NGS)
considers the orthometric markers in Louisiana surveyed every decade for the
North American Vertical Datum (NAVD) to be “obsolete.” Dokka
and his colleagues, together with experts from the NGS, are
now using high-powered transponders and numerous Global Positioning System
satellites to develop “true” elevation points in the state on the basis of their
relation to the center of the earth.

Using a rate of subsidence measured at a tidal gauge off the coast of Grand
Isle adjacent to an original NAVD marker, Dokka was able to
calibrate rates of subsidence at hundreds of other markers around the state. His
results indicate that the elevations of some areas have dropped as much as 2 ft
(0.6 m) since they were last surveyed for the NAVD. Based on
Dokka’s “true” elevations, some of the Corps’s levees in New Orleans may be more
than 1 ft lower than their posted elevation.

And the sinking continues. In the next 70 years, Dokka and his colleagues
estimate that about 15,000 sq mi (39,000 km2) of land in southern
Louisiana will be at or below sea level. In the same amount of time, some of the
areas in and around New Orleans will have subsided by 3 ft (0.9 m).

“New Orleans is right there,” Dokka says, pointing to a graphic illustration
of his research on a computer screen. “But I guarantee you that won’t last,
because the ocean is right there on both sides, and any kind of storm is going
to take out that area.”

Such dire predictions would seem to favor a drastic solution, such as the
Coast 2050 Plan. But Dokka is not easily convinced. “They’re not going to dump
freshwater on the areas where people live,” he says. “Even if they haul up the
flag of victory and save the wetlands, these areas where people live will not be
saved.”

Instead, Dokka proposes an even more ambitious alternative. In 100 years, he
says, subsidence will have made Lake Pontchartrain and Lake Borgne one large
lake bordering New Orleans to the north and east and opening into the Gulf of
Mexico. By diverting the Mississippi into the lake and using sediment from the
river like “a big cement truck” to build up a protective boundary along its
north shore, engineers could create “the world’s greatest harbor.”

“It’s all going to be artificial in the end anyway,” Dokka says. “People are
just beginning to discover what is happening here. But nature wins. Nature
always wins in the end. It doesn’t give up. It just keeps on going.”

ut the Coast 2050 Plan currently has widespread support
among environmentalists, the oil and gas industry, and hurricane protection
specialists.

People such as Windell Curole consider it the last, best chance to save
southeastern Louisiana. Curole (pronounced “cure-all”) is the general manager of
the South Lafourche levee district, which maintains hurricane protection levees
around Bayou Lafourche, a rural area west of New Orleans and the place where he
was raised. Decades ago Curole’s grandfather paddled through the wetlands there
in a hollowed-out cypress tree collecting oysters. Today much of the same area
is completely submerged in salt water.

On a recent sunny morning, Curole visited a freshwater diversion project near
New Orleans called Davis Pond, one of only two such diversions from the
Mississippi River. The project involves a canal west of the city that releases
about 1,000 cfs (28 m3/s) of freshwater from the top of the river
into a 9,300 acre (3,700 ha) pond that eventually feeds into Lake Cataouatche.
By filling the marsh with freshwater, the idea is to decrease its salinity while
feeding it valuable nutrients, in this way mimicking the marsh environment that
would have existed before the sides of the Mississippi were dammed.

First authorized by Congress in the late 1960s, Davis Pond was completed by
the Corps in March 2002. In the 1960s it was seen as a fairly aggressive step
toward addressing the issue of coastal erosion. Today, in Curole’s words, it is
seen more as a “Band-Aid.” The project—which does not divert sediment into the
marsh in any measurable quantity—is meant to alleviate a total of about 1 sq mi
(2.6 km2) of land loss. By most estimates, coastal Louisiana is
losing as much as 35 sq mi (90.6 km2) of land per year to subsidence.
Despite this grim reality, Curole refuses to see anything in Davis Pond except
signs of hope. “It’s a little leak for the river,” he says, looking over the
water, “but a giant leak for mankind.”

This is Curole’s first trip to Davis Pond, a place that he and other
supporters of the Coast 2050 Plan hope will be viewed as a sort of pilot project
for future diversion efforts. Traveling by airboat over thick, floating marshes
and rounded levees, he enthusiastically points at countless alligators,
scurrying nutrias, and several bald eagle nests. He snaps pictures of waterfowl
as if he has never seen them before, or, more likely, as if he might never see
them again.

The boat stops at the end of the pond near a rock weir separating it from
Lake Cataouatche, the New Orleans skyline in the distance. “It’s just so nice to
see the growth here, the green growth,” Curole says. Smiling large, eternally
optimistic, he continues: “If we run this thing harder, up to six thousand cfs,
or even more, I think we’ll start seeing white shrimp up in here again. That is
a major hurdle. If we can start running this at six thousand cfs, who knows what
we can do.”